Shrinkproofing wool fabrics

ABSTRACT

A method for rendering wool fabric shrink resistant comprising treating the fabric with an aqueous emulsion of chain-extended urethane pre-polymers in surfactant-containing aqueous solution, drying the fabric, and thereafter curing the treated fabric.

nited States Patent lodger et al.

[ 3,61 ,002 [451 Apr. 1972 [54] SHRINKPROOFING WOOL FABRICS [72] Inventors: John D. Blodger; Ian MacGugan, both of [21] Appl. No.: 851,772

[52] U.S.Cl. ..117/141,111/161KP [51] Int. Cl. ..D06C 29/00, D06m 15/52 [58] Field 0156811211 ..117/141, 161KP;260/29.2 TN, 260/775 A; 8/l27.6, 128 R [56] I References Cited UNlTED STATES PATENTS 2,395,791 2/1946 Pfeffer et a1. ..117/141 X 2,678,286 5/1954 Brunet et al ..117/141 2,696,448 12/1954 Hammer et al. ..117/141 2,817,602 12/1957 Pardo ..117/141 2,961,347 11/1960 Floyd ..117/141 2,992,944 7/1961 Binkley ..117/141 3,019,076 l/1962 Pardo et a1 ..117/141 X 3,084,018 4/1963 Whitfield et a1. ..8/127.6 X 3,357,785 12/1967 Garber et a1 ..117/141 X 3,385,653 5/1968 Whitfield et al. ..117/141 X 3,401,133 9/1968 Grace et a1 ..117/161 X 3,410,817 11/1968 McClellan et a1 ..117/143 X 3,489,744 1/ 1970 Schwarcz ..117/161 X FOREIGN PATENTS OR APPLlCATIONS 1,128,568 9/ 1968 Great Britain ..260/29.2

Primary Examiner-William D. Martin Assistant Examiner-Harry J. Gwinnel Attorney-Bemhard R. Swick, Robert E. Dunn, Joseph D. Michaels, Charles G. Lamb and Gerard G. Weil [5 7] ABSTRACT A method for rendering wool fabric shrink resistant comprising treating the fabric with an aqueous emulsion of chain-extended urethane pre-polymers in surfactant-containing aqueous solution, drying the fabric, and thereafter curing the treated fabric.

11 Claims, No Drawings snnmxrnoormo WOOL rxmucs treating wool fabrics with a polyurethane latex to render the fabrics shrink resistant.

Many methods have been proposed to obviate the problem of shrinkage in fabrics such as wool flannel, worsted and wool flannel and the like. For example, US. Pat. No. 3,084,018 discloses a method for inhibiting wool shrinkage wherein a polyurethane is formed in situ on the fibers by sequentially or serially reacting a diamine and a bischloroformate. This process chemically bonds the polyurethane to the wool. However, this process alters the basic chemical composition of the fiber, thereby reducing the strength of the fiber and the fabrics produced therefrom.

ln Canadian Pat. No. 816,026, there is disclosed a twostep method for shrinkproofing wool fabrics and the like wherein a solution of an isocyanate-modified hydroxy compound is applied thereto and thereafter is cured with water. However, this process requires the use of an organic solvent for the solution. The use of an organic solvent in fabric treatment has many disadvantages such as the cost of the solvent; cost of solvent recovery; flammability of the solvent; toxicity of the vapors emanating from the solvent and the like.

In industrial applications, the most prevalent method employed for shrinkproofing wool fabrics comprises contacting the fabric with dichloroisocyanuric acid, acidifying the treated wool, dechlorinating the wool and then washing the wool a plurality of times to remove any excess reagents. This method chemically alters the fabric while concurrently reducing the strength thereof. Moreover, this process requires a multitude of steps to render the fabric shrink resistant.

It is readily seen that all these processes either provide for the strength-reducing chemical alteration of the fabric and/or they require multi-stage processes which are economically disadvantageous.

It is, therefore, an object of the present invention to provide an improved method for imparting shrink resistance to wool fabrics and the like. It is another object of the present invention to provide a method for shrinkproofing wool fabrics without altering the chemical nature thereof. Another object of the present invention is to provide a method for treating wool fabrics with a polyurethane latex. A still further object of the present invention is to provide polyurethane-treated, shrink resistant wool fabrics. It will become apparent to those skilled in the art that these and other objects are achieved by the present invention from a consideration of the following detailed description and examples.

In accordance with the present invention, it has been found that wool fabrics such as wool flannel and worsted and wool flannel are provided with improved shrink resistance by a process comprising (a) contacting the fabric with a polyurethane latex bath, (b) drying the fabric, and (c) thereafter, curing the latex treated fabric.

It has been found that the use of a latex provides many advantages not obtainable with the prior art methods. For example, as noted, many of the prior art methods of shrink proofing wool fabrics results in a reduction of the fabric strength. The polyurethane latices employed in the present invention do not in an way reduce the strength of the fabrics. Moreover, it has been observed that fabrics treated in accordance with the present invention have improved properties such as increased abrasion resistance and the like. Additionally, the latex treatment need be conducted only once, whereas in many instances the prior art processes require multiple treatments for imparting necessary shrink resistance.

The polyurethane latices contemplated for use herein generally comprise emulsions of chain-extended urethane prepolymers in surfactant-containing aqueous solutions. Generally speaking, the latices have from about 48 to 52 per- Preferably, the latices comprise about 50 percent solids by weight.

The urethane prepolymers employed in the preparation of the latices used in the present invention preferably comprise NCO-terminated prepolymers obtained by reacting a polyalkylene ether polyol with an excess amount of an organic diisocyanate.

The polyalkylene ether polyols employed herein have a functionality greater than two and are obtained from the reaction of an alkylene oxide and a compound having at least three reactive hydrogen atoms. Furthermore, the preferred polyols have an equivalent weight of at least 500 (molecular weight of the polyol per hydroxyl group). Alkylene oxides that can be employed in the preparation of the polyols are those having at least three carbon atoms, such as, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, cyclohexene oxide and mixtures thereof. Ethylene oxide may also be used in combination with any of these alkylene oxides provided that the alkylene oxide mixture contains no more than 50 percent by weight of ethylene oxide.

Compounds having at least three active hydrogen atoms which may be employed in the preparation of the polyalkylene ether polyols include aliphatic alcohols such as glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose; organic acids such as aconitic, trimellitic and hemimellitic; inorganic acids such as the phosphoric acids; amines such as ethylene diamines, propylene diamine, diethylene triamine and triisopropanolamine; phenolic compounds such a pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acids and inositol mercaptans such as 1,2,3-propane trithiol and amides such as benzene disulfonamide. Mixtures of any of the above compounds may also be employed.

The polyalkylene ether polyols are prepared by standard art procedures such as catalytic polymerization of the oxide and the compound having at least three active hydrogen atoms. An alkaline catalyst such as potassium hydroxide is often employed in this polymerization.

If it is desired to improve the tensile and tear strength of the polymers prepared from the latices of this invention, diols may be employed along with the polyols in the preparation of the latices. Any of the diols which are known in the art are suitable for this purpose, especially polyalkylene ether diols, for example polypropylene glycol.

Organic diisocyanates which may be employed in the preparation of the polyurethane latices of this invention include aromatic, aliphatic, and alicyclic diisocyanates and combinations thereof. Representative compounds include aromatic diisocyanates, such as 2,4-tolyene diisocyanate, mixtures thereof with 2,6-tolylene diisocyanate (usually about /20), 4,4-methylene-bis(phenylisocyanate), and m-phenylene diisocyanate. Aliphatic compounds such as tetramethylene diisocyanate and hexamethylene diisocyanate, and alicyclic compounds such as 1,4-cyclohexylene diisocyanates and 4,4-methylene-bis-(cyclohexylisocyanate) are also operable. Compounds such as 2,4-tolylene diisocyanate in which two isocyanate groups differ in reactivity are particularly desirable. The diisocyanates may contain other substituents, although those which are free from reactive groups other than the two isocyanate groups are ordinarily preferred. In the case of the aromatic compounds, the isocyanate groups may be attached either to the same or to different rings. Additlolal diisocyanates which may be employed, for example, inclu e V 3,3'-dimethyl-4,4'-biphenylene diisocyanate,

3,3-dimethoxy-4,4'-biphenylene diisocyanate,

4,4'-biphenylene diisocyanate,

4-dichlorol ,3-phenylene diisocyanate,

3,3'-dichloro-4,4'-biphenylene diisocyanate, and

1,5-naphthalene diisocyanate, and other diisocyanates in a blocked or semi-inactive form such as the bis-phenylcarbamates or tolylene diisocyanate, p,p' diphenyl-methane diisocyanate, p-phenylene diisocent solids based on the total weight of the solution. 7 cyanate and l,5-tetrahydro-naphthalene diisocyanate.

The prepolymer is prepared by conventional procedures well known in the art, such as the catalytic reaction of the diisocyanate and the polyalkylene ether polyol.

The reaction is also preferably carried out, but not necessarily, in the presence of a solvent. Convenient solvents are the standard art organic solvents having a boiling range above 90 C. when the reaction is carried out in closed equipment to prevent boiling off the solvent at the temperatures of the reaction. The solvent, when used, may be added at any convenient point of the prepolymer formation or after cooling of the formed prepolymer. The solvents to be used are preferably those in which the reactants are soluble. Hydrocarbon solvents such as toluene and benzene are preferred. The amount of solvent used may be varied widely. From 25 parts to 400 parts of solvent per 100 parts of polyol have been found to be satisfactory. Excess solvent, where large amounts are employed may be separated partially or completely from the polymer prior to emulsification in the water solution.

The amounts of organic diisocyanate and polyalkylene ether polyol which are employed in the preparation of the prepolymers are such that the NCO/OH equivalent ratio is between 1.121 to 30:1, preferably 2:1. At ratios greater than 3.0:1, incompatible resins tend to form, while at ratios less than 1.1:1 gelling of the polymer tends to occur.

After the prepolymer is prepared, it is emulsified by combining it with an aqueous solution of a surfactant with vigorous agitation. Emulsification of the prepolymer may occur by adding an aqueous solution of a surfactant to the prepolymer, by adding the prepolymer to an aqueous solution of a surfactant, by initially adding a surfactant to the prepolymer reactants and then adding water after the prepolymer has been prepared or by adding a surfactant to an aqueous medium containing the prepolymer.

Any emulsifying agent which will give oil-in-water emulsions is satisfactory for use in the present invention. Non-ionic surface active agents such as polyoxyethylene-polyoxypropylene glycols, and the reaction product of a polyethylene glycol and an aromatic diepoxide such as the reaction product of a polyethylene glycol with the epichlorohydrin and Bisphenol A, 2,2-bis(4-hydroxyphenyl)prpane, are preferred.

Chain extension of the prepolymer occurs by adding a chain-extending agent to the emulsified prepolymer. Where the polyol used in the preparation of the prepolymer has an equivalent weight of from about 500 to 2,500 (molecular weight of the polyol per hydroxyl group), it is desirable to employ a chain-extending agent which comprises a mixture of a compound having one active hydrogen atom and a compound having two active hydrogen atoms. When the polyol has an equivalent weight in excess of about 2,500, a compound having two active hydrogen atoms is preferably employed as the chain-extending agent.

The chain-extending agent, either the mixture or single component alone, is preferably added in the form of an aqueous solution or dispersion thereof. However, in those instances where the chain-extending agent comprises the mixture, it is possible to add the compound having one active hydrogen atom to the hydroxyl-containing component during prepolymer preparation and then, after emulsifying the prepolymer, to add the compound containing at least two active hydrogen atoms. This procedure is generally employed when a compound having a hydroxyl group is used as the compound having one active hydrogen atom.

Examples of compounds having one active hydrogen atom include alcohols such as methyl alcohol, butyl alcohol, lauryl alcohol and benzoic alcohol, trichlorinated isopropanol and fluorinated alcohols; mercaptans such as butyl mercaptan and lauryl mercaptan; acids such as acetic acid, nonyl acid and lauric acid; alkylene oxide condensates of alkyl phenols such as the 1 to 50 mole adducts of ethylene oxide an octyl phenol, and secondary amines such as dibutylamine, methylethylamine and morpholine. The particular compound employed is not critical. All that is important is that the compound have one active hydrogen atom.

condensate of Examples of compounds having at least two active hydrogen atoms include water, primary and secondary diamines such as phenylene diamine, 1,4-cyclohexane-bis-(methylamine), ethylene diamine, N-(Z-hydroxypropyl) ethylene diamine, N,N'-di(2hydroxy-propyl)ethylene diamine, piperazine, 2- methylpiperazine and dodecahydrol ,4,7 ,9btetraazaphenaline; triamines such as diethylene triamine and triisopropanolamine; amino acids such as glycine, alanine, lysine, phenylalanine and cystine; hydroxy acids such as hydroxyacetic, glycolic, hydroxybutyric, lactic and hydroxyvaleric acids; and polyols such as 1,4-butane diol, ethylene glycol, 1,4-cyclohexanedimethanol, hexane diol, trimethylolpropane, glycerol and alkylene oxide adducts or any of the above polyols. Mixtures of the above may also be employed. Compounds having two active hydrogen atoms such as 2- methylpiperazine are preferred.

The total amount of chain-extending agent which is employed in the preparation of the latices is preferably about 1.0 equivalent of chain-extending agent for each isocyanate equivalent. Up to about 1.25 equivalents of chain-extending agent for each isocyanate equivalent may be employed. In those instances where the polyol has an equivalent weight of from about 500 to 2500, and the chain-extending agent comprises the mixture, from about 0.05 to about 0.5 equivalent of chain-extending agent per isocyanate equivalent comprises the compound having one active hydrogen atom. Stated otherwise, the mixture of chain-extending agents will comprise from 5 to 50 percent of equivalents derived from the compound containing one active hydrogen atom, based on the total equivalents present. The chain-extension step may frequently be assisted by agitation of the emulsion for some time after its initial inception. This is usually accomplished by any conventional means which aids in contacting the emulsion droplets with the chain-extender.

In preparing the latices sufficient water is provided to obtain latices having a solids content of from 48 to 52 percent by weight, preferably a solids content of about 50 percent by weight.

For a more comprehensive discussion of the polyurethane latices employed in the present invention, US. Pat. Nos. 3,401,133 and 3,410,817, which are incorporated herein by reference, may be referred to.

In carrying out the process of the present invention, a latex bath having about a five to ten percent solids content is employed. The bath is prepared by diluting any one of the abovedefined latices with water. In rendering a wool fabric shrink resistant, the fabric is generally contacted with the bath for a period of about one to five minutes, preferably for about two to three minutes, and at room temperature. The fabric is preferably contacted with the latex bath by a padding process which essentially comprises immersing the fabric in the bath and thereafter removing any excess bath solution therefrom. Padding processes are well known in the art and any such conventional technique can be employed.

After padding it is desirable that the fabric have a wet pickup of from about 92 to 97 percent, about a percent wet pick-up is desirable. Wet pick-up is defined by the equation:

Wet Weight of FabricDry Weight of Fabric Percent Wet Pick Up= After the fabric is padded it is then dried and cured. Drying is effectuated in any conventional manner such as by disposing the padded fabric in an oven or the like for a period of about 5 to 25 minutes and at a temperature of from about 100 to 120 F. Preferably, the drying step is conducted at a temperature ranging from to 1 15 F. for about 5 to 15 minutes.

After drying, the fabric has about 2 to 3 percent dry solids pick-up. The percent of dry solids pick-up is based on the weight of the dry fabric and can be determined either mathematically or by merely measuring the weight of the dried fabric and comparing it to the original weight of the fabric. Mathematically, percent dry solids pick-up is detennined in accordance with the following equation:

Wet Weight of Fabric Dry Weight of Fabric X Percent Solids in Latex ighif fsb Thereafter, the fabric is cured by heating the latex treated fabric in an oven or the like and at a temperature of from about 250 to 300 F. for about to minutes. Preferably, the fabric is cured for about 5 to 7 minutes and at a temperature ranging from about 260 to 280 F. After the cure stage, the fabric is ready for use.

Wool fabrics treated in accordance with the present invention exhibit, after five household washings and dryings, no more than four percent total shrinkage and usually from two to three percent total shrinkage. By the term total shrinkage is meant the sum of the warp shrinkage and the fill or weft shrinkage excluding shrinkage due to padding which is inherent in fabric treatment. Moreover, as hereinbefore mentioned, fabrics treated in accordance with the present invention exhibit improved abrasion resistance and the like.

The following examples serve to illustrate the advantages accruing to wool fabrics treated in accordance with the present invention.

Percent Dry Solids PickUp= X 100% EXAMPLE I A l2" 12" sample of a worsted and wool flannel fabric was padded to 95 percent wet pick-up by immersing the sample in a poly-urethane latex bath and then wringing the fabric through a conventional clothes washer-type wringer. The latex bath consisted of 400 parts of water and 100 parts of a 50 percent solids latex. The latex, which was made in accordance with Example VIII of US Pat. No. 3,410,817, consisted of a chain-extended NCO-terminated prepolymer prepared by reacting at an NCO/OH ratio of 2: 1, a 6,120 molecular weight propylene oxide adduct of trimethylolpropane and tolylene diisocyanate. The prepolymer was prepared in the presence of toluene (as a solvent) and was chain-extended with 2-methylpiperazine. The surfactant employed in preparing the latex consisted of a dihydric polyoxyethylene-polyoxypropylene having a molecular weight of 16,000, a polyoxyethylene content of about 80 percent and a polyoxypropylene base of about 3,250 molecular weight.

After being padded with the latex bath, the sample was placed in an air-circulating oven and dried at 1 10 F. for about 10 minutes. After drying, the sample had a 3 percent dry solids ick-u p The sample was tested for shrinkage in accordance with the following washing and drying procedure. Using a domestic laundry washing machine, the sample was washed with a domestic synthetic detergent, and thereafter was rinsed and spun dry. The washing cycle lasted for about 10 minutes and at a temperature of about 140 F., and the drying cycle for 30 minutes at 120 F.

The washing and drying procedure was thereafter repeated using a control sample of wool and worsted flannel which was not treated in accordance with the invention, but rather was padded with a water bath.

Measurements of warp and fill were taken on both samples after padding the fabric and the first and fifth wash and dry cycles. The measurements were then compared to the original measurements of the samples and percent shrinkage was thereby determined. Table 1, below, sets forth the results of the tests.

"S (total shrinkage shrinkage due to padding) It can be seen from the data that after the first cycle, he treated fabric shrunk only 2 percent, whereas the untreated fabric shrunk 4 percent. After the fifth wash and dry, shrinkage for the untreated fabric was 8 percent and the treated fabric shrunk only 3 percent. It is thus seen that treatment of a wool fabric in accordance with the present invention significantly reduces the shrinkage thereof.

EXAMPLE II The procedure of Example I was repeated except that the latex employed in the preparation of the bath was made substantially in accordance with Example 13 of US. Pat. No. 3,401,133. The latex was made by chain-extending with 2- methylpiperazine and the five mole adduct of ethylene oxide and octylphenol an NCO-terminated prepolymer prepared from the reaction of a blend of polyols and tolylene diisocyanate. The polyol blend consisted of l) a 6,150 molecular weight propylene oxide adduct of trimethylolpropane and (2) a 666 molecular weight diol prepared from propylene oxide and Bisphenol A. The solvent employed in the prepolymer preparation was toluene. The surfactant used in preparing the latex was the reaction product of a polyethylene glycol and an aromatic diepoxide. parts of the latex, which had a solids content of 50 percent, was diluted with 400 parts of water to prepare the latex bath used herein.

The results of shrink measurements for both a control sample and a treated sample are set forth below in Table 2.

TABLE 2 Shrinkage Shrinkage Shrinkage After After First After Fifth Sample Padding Wash & Dry 7c S Wash & Dry %S Control 5% 9% 4% 13% 8% Treated Fabric 4% 6% 2% 7% 3% Again, it is seen that the use of a polyurethane latex as a fabric treatment provides a significant reduction in the amount of fabric shrinkage.

EXAMPLES III-IV TABLE 3 Shrinkage Shrinkage Shrinkage After After First After Fifth Sample Padding Wash 8: Dry S Wash & Dry 5 Control 5% 9% 4% 12% 7% Sample 1 5% 6% 1% 7% 2% Sample 2 4% 7% 3% 7% 3% It can be seen from the data that the present invention provides a method for significantly reducing the amount of shrinkage in worsted flannel fabrics.

What is claim:

11. A method for rendering a wool fabric resistant to shrinkage comprising the steps of:

a. padding said fabric with a polyurethane latex bath, said bath containing from about five to ten percent by weight of solids, said bath being prepared by diluting with water a polyurethane latex having from about 48 to 52 percent solids by weight, said latex prepared by the chain-extension of an NCO-terminated prepolymer prepared by the reaction, in an NCO/OH equivalent ratio of from 1.1:1 to 3.0: l of an organic diisocyanate with a polyalkylene ether polyol having a functionality greater than two and an equivalent weight of at least 500, said polyol being prepared from an alkylene oxide having at least three carbon atoms or a mixture of alkylene oxides having at least 50 percent by weight of an alkylene oxide having at least three carbon atoms and a compound having at least three reactive hydrogen atoms,

b. drying said fabric for about to 15 minutes and at a temperature ranging from 100 to 120 F., and, then,

c. curing said fabric at a temperature ranging from 260 to 280 F. for a period of about 5 to minutes.

2. The method of claim 1 wherein said fabric is padded to about a 92 to 97 percent wet pick-up weight based on the dry weight of said fabric and after drying said fabric has deposited thereon from about 2 to 3 percent dry solids pick-up based on the dry weight of said fabric.

3. The method of claim 2 wherein the polyalkylene ether polyol is the reaction product of propylene oxide and a trihydric alcohol.

4. The method of claim 2 wherein the poly-alkylene ether polyol is the reaction product of propylene oxide and 8 trimethylolpropane.

5. The method of claim 2 wherein said prepolymer is chainextended with about 1.0 equivalent of a chain-extending agent being selected from the group consisting of (I) an organic compound having at least two active hydrogen atoms and (2) a mixture of an organic compound having at least two active hydrogen atoms and an organic compound having one active hydrogen atom.

6. The method of claim 5 wherein the prepolymer is chainextended with a 2-methylpiperazine.

7. The method of claim 5 wherein said prepolymer is prepared by the reaction of an organic diisocyanate with a poly-alkylene ether polyol having a functionality greater than two and an equivalent weight of at least 500 to about 2,500, and said chain-extending agent is said mixture which contains from 0.05 to 0.5 equivalent per isocyanate equivalent of an organic compound having one active hydrogen atom.

8. The method of claim 7 wherein the organic diisocyanate is tolylene diisocyanate.

9. The method of claim 7 wherein the polyalkylene ether polyol is prepared from propylene oxide and trimethyloipropane.

10. The method of claim 7 wherein the organic compound having one active hydrogen atom is ethoxylated octylphenol.

11. The method of claim 7 wherein the organic compound having at least two active hydrogen atoms is Z-methylpiperazine. 

2. The method of claim 1 wherein said fabric is padded to about a 92 to 97 percent wet pick-up weight based on the dry weight of said fabric and after drying said fabric has deposited thereon from about 2 to 3 percent dry solids pick-up based on the dry weight of said fabric.
 3. The method of claim 2 wherein the polyalkylene ether polyol is the reaction product of propylene oxide and a trihydric alcohol.
 4. The method of claim 2 wherein the poly-alkylene ether polyol is the reaction product of propylene oxide and trimethylolpropane.
 5. The method of claim 2 wherein said prepolymer is chain-extended with about 1.0 equivalent of a chain-extending agent being selected from the group consisting of (1) an organic compound having at least two active hydrogen atoms and (2) a mixture of an organic compound having at least two active hydrogen atoms and an organic compound having one active hydrogen atoM.
 6. The method of claim 5 wherein the prepolymer is chain-extended with a 2-methylpiperazine.
 7. The method of claim 5 wherein said prepolymer is prepared by the reaction of an organic diisocyanate with a poly-alkylene ether polyol having a functionality greater than two and an equivalent weight of at least 500 to about 2,500, and said chain-extending agent is said mixture which contains from 0.05 to 0.5 equivalent per isocyanate equivalent of an organic compound having one active hydrogen atom.
 8. The method of claim 7 wherein the organic diisocyanate is tolylene diisocyanate.
 9. The method of claim 7 wherein the polyalkylene ether polyol is prepared from propylene oxide and trimethylolpropane.
 10. The method of claim 7 wherein the organic compound having one active hydrogen atom is ethoxylated octylphenol.
 11. The method of claim 7 wherein the organic compound having at least two active hydrogen atoms is 2-methylpiperazine. 